23 September 2011

EFFECT OF FROST ON THE HEAT TRANSFER OF FIN-TUBE WITH MULTIPLE FINS


The present study investigated frost characteristics of a fin-tube with multiple fins
for heat pump application under heating condition. The key parameters were number of fins.
Key experimental conditions were air temperature of 2?, absolute humidity of air of
3.67g/kgDA, air velocity of 0.5m/s, and surface temperature of the refrigerant of -10?. The
coolant was 50% ethylene-glycol aqueous solution.
Local frost thickness and frost mass were measured for the fin-tube modelled as large scale
for easy measurement. The frost thickness is influenced on air flow and fin surface
temperature. Moreover, the frost thickness for the case of 1 fin can be predicted using
dimensionless correlations. However, it is difficult to predict the frost growth using present
dimensionless correlations with growing fin number due to difficulty in measurement of all fin
surface temperature or change in air flow cased by boundary layer between fins. After
solving these problems, frost growth on the whole heat exchanger can be predicted with
prediction of frost growth for the case of multiple fins using fin by fin method.